1. Field of the Invention
The present invention relates to a semiconductor device including current sense cells.
2. Description of the Related Art
Power devices typically include a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) and an IGBT (Insulate Gate Bipolar Transistor). When excess current caused by short-circuit or the like flows in such the power device, it breaks down the power device. Accordingly, it is required to control excess current not to flow in the power device. When a power device is employed to control the rotation of a motor, it is required to control current flowing in the power device precisely. For these purposes, a current sensor is provided separately from the power device. In general, a resistor is connected between the power device and the current sensor to sense a potential between both for current sensing.
When a current sense cell, or the current sensor, is formed on a single chip together with the power device (main cell), external components such as a current probe are not required and the device can be downsized. See JP-A 7-240520 (FIG. 1), JP Patent No. 3400237 (FIGS. 1-3, 6-8), and JP Patent No. 3450650 (FIGS. 1-4, 7, 8). In this case, however, no potential locates across the current sense cell and the main cell if the current sense cell is isolated from the main cell, and no current can be sensed. On the other hand, it is required to ensure the area of a region (sense region) formed to arrange the current sense cell therein.